The worst-case scenario for the Islanders is Griffin Reinhart becomes this year’s Nino Niederreiter.

Reinhart was the No. 4 overall pick in the 2012 draft, and the 6-foot-4 defenseman is still with the Islanders for the third game of this season not just by the fortune of a misguided rule, but because he deserves to be.

Throughout training camp, the 19-year-old Reinhart impressed coach Jack Capuano and general manager Garth Snow with his intelligence on the ice, his vision with the puck and his poise away from it. Yet in Tuesday night’s game against the Coyotes at the Coliseum, Reinhart was set to be a healthy scratch for all three games.

Because of his age, Reinhart is not eligible to play for AHL Bridgeport, a rule that exists in order to preserve the junior ranks as a more competitive atmosphere for prospects. He can play up to nine games with the Islanders, yet after that, if Reinhart can’t stick it in the NHL, he will be forced to go back to his junior team, the Edmonton Oil Kings of the WHL, with whom everyone knows he cannot continue to develop at the proper pace.

“It’s a little frustrating not playing, but I’ve been in junior several years now, and I don’t think there’s too much more for me to be learned down there,” Reinhart told The Post on Tuesday morning. “So I think just practicing here — even if I was just practicing here all year, and playing a few games — I’d learn more from these guys than going back to junior.”

It is the same bad situation that forced Capuano and Snow to keep Niederreiter two seasons ago, when the No. 5 overall pick of the 2010 draft played 55 games in the NHL and astonishingly — with all of his talent — had just one goal, in his first game, and zero assists, while playing to a minus-29 rating.

“With Griff, I talked to Garth a little bit and we’ll decide as we move forward,” Capuano said. “He’s gaining that experience, he’s going through the practices. The pace is good, he’s learning what it is to be a pro. This is really good experience for him.”

Though Capuano may not readily admit it, what happened with Niederreiter can’t be far from his mind. After that horrid season in the NHL, Niederreiter spent the next year playing a middling game in the AHL and became disgruntled, sternly asking the team to trade him.

They did deal Niederreiter this offseason to the Wild in exchange for rugged forward Cal Clutterbuck, 25, whom they then signed to a four-year, $11 million deal.

And, ironically enough, it’s Clutterbuck who is now expediting the decision on Reinhart. Having suffered a bad leg laceration in the first preseason game, Clutterbuck is expecting to make his Islanders debut Friday in Chicago against the defending Stanley Cup champion Blackhawks.

Once he comes off the injured reserve, someone will need to move in order to make a roster spot.

That might mean Reinhart going back to juniors, and it might not. Capuano was not ready to declare either way, and a team source said the company line of taking the decision “day-by-day” is a reality — not like there’s any other option, anyway.

There are other options to make room on the roster, as well — placing Thomas Hickey, Matt Carkner or Eric Boulton on waivers, for instance — but those options risk losing a player on the current roster. They could send rookies Matt Donovan or Brock Nelson back to Bridgeport, but both impressed in the first two games.

“There are other guys, too, with the exception of Griff, who we want to get in there,” Capuano said. “You have to fight for you job and ice time. But with him, it’s a little bit different.”

Different than what happened with Niederreiter is the best thing Capuano and Snow can hope for.

@NYI FANCENTRAL I know Nino requested a trade, and wrote it when it happened. He may have been an All-star in the AHL because of his point production, but people didn't believe that translated into an all-around game in the NHL. And Kreider, who mentioned him?

@Brett Cyrgalis@NYI FANCENTRAL His agent made one twitter comment requesting a trade. The Ct Post folows team and beat writer Michael Fornabaio had his direct comments about this many times where he requested nothing.

Who are these people again because they were not in Bridgeport?

Middling results is not an All-Star with his production on a struggling team.

Hey Brett, not sure how much hockey you actually watch, but many of the top scorers in the NHL do not have what knowledgable hockey people would call an all around game. Who are these "people" that didn't believe in Nino? Wang and Snow? Oh, and by the way, most forwards make the all-star team because of point production, goals and assists are kinda important as you see the team with the most goals usually wins the game. Your writing makes Staple look like a savant.